Tony Dickerson problem solves
QCan you tell me what the tiny, slug-like creatures on my blueberry shrub are?
AThese could simply be tiny slugs but I fear you may be looking at the maggots of the spotted winged drosophila fruit fly ( Drosophila suzukii or SWD for short). This is a native of South East Asia and was first reported in the UK in 2012.
The female lays eggs under the surface of fruit, and these turn into small white larvae 4mm in length. This pest affects a wide range of fruit, but the first symptoms you’ll notice are small puncture wounds on the fruit, or the fruit collapsing.
The best way to prevent damage from SWD is to monitor fruit to see if adults are targeting it. SWD traps and lures are available from Agralan stockists (tel: 01285 860015 to find your nearest one). If SWD adults are found, stop them from causing damage by using fine mesh netting with a diameter of less than 1mm, such as horticultural fleece or Enviromesh Ultrafine. Keep trapping and monitoring until the end of November, even if crops have finished, to reduce populations for next season.
In addition to trapping, garden pesticides can be used to help control the adults, although their use is unlikely to completely eliminate the fly. The most effective control is a combination of monitoring, trapping and spraying. Don’t spray plants in flower due to the danger to pollinators. Some products that can be used on a range of fruit are natural pyrethrum/ pyrethrins (such as Bug Clear Fruit & Veg Gun, Defenders’ Bug Killer), deltamethrin (like Bayer Provado Ultimate Fruit & Vegetable Bug Killer, Bayer Sprayday Greenfly Killer) and lambda-cyhalothrin (Westland Resolva Bug Killer).
Other than that, pick fruit as soon as it’s ripe and don’t allow old, damaged or diseased fruits to remain on the plants, or lie on the ground. After removing overripe fruits and all associated waste, dispose of it responsibly in sealed plastic bags. Don’t throw waste and infected fruit on your compost heap as this could attract more SWD.